In medical computerized tomography (CT), a large number of X-ray images are taken from different angles of a part of the body of a patient. Using the mathematical procedure of tomographic reconstruction, the X-ray images are processed and combined to yield cross-sectional images of the part of the body, providing a non-invasive three-dimensional (3D) image of the internal structure of the imaged part.
U.S. Pat. No. 7,630,529, which is incorporated herein by reference, describes a system for performing a virtual colonoscopy that is stated to include a system for generating digital images, a storage device for storing the digital images, a digital bowel subtraction processor coupled to receive images of a colon from the storage device and for removing the contents of the colon from the image and an automated polyp detection processor coupled to receive images of a colon from the storage device and for detecting polyps in the colon image.
U.S. Patent application 2014/0330115, which is incorporated herein by reference, describes a method for displaying a paranasal sinus region of a patient that is executed at least in part on a computer. The method is stated to include acquiring volume image data of the paranasal sinus region of the patient, identifying one or more airways within the paranasal sinus region from the volume image data, displaying the at least one or more airways, and highlighting one or more portions of the displayed airways that are constricted below a predetermined value.
U.S. Patent application 2013/0004044, which is incorporated herein by reference, describes a voxel-based technique that is provided for performing quantitative imaging and analysis of tissue image data. Serial image data is collected for tissue of interest at different states of the issue. The collected image data may be deformably registered, after which the registered image data is analyzed on a voxel-by-voxel basis, thereby retaining spatial information for the analysis. Various thresholds are applied to the registered tissue data to identify a tissue condition or state, such as classifying chronic obstructive pulmonary disease by disease phenotype in lung tissue, for example.
U.S. Patent application 2008/0008367, which is incorporated herein by reference, describes how an image of an anatomical structure can be analyzed to determine an enclosing three-dimensional boundary when the anatomical structure is filled with two substances, such as air and a fluid. Various techniques can be used to determine the enclosing boundary including: analyzing the virtual structure to segment the structure into air and fluid pockets, determining if there are multiple fluid pockets whose surface touches a single air-fluid boundary, determining a separate threshold for respective fluid pockets, resegmenting the virtual anatomical structure using the separate threshold for different fluid pockets, forming a hierarchical pocket tree which represents the relationship between the fluid and air pockets, pruning the pocket tree based on various criteria which corresponds to deleting those pruned portions from the virtual anatomical structure, and resegmenting the remaining virtual anatomical structure using one or more of fuzzy connectedness, two-dimensional gap filling, and level set segmentation.
Documents incorporated by reference in the present patent application are to be considered an integral part of the application except that, to the extent that any terms are defined in these incorporated documents in a manner that conflicts with definitions made explicitly or implicitly in the present specification, only the definitions in the present specification should be considered.